From Passing the Hat To the Big Time. Ex-rappers now range from ballads to `hiphop'. THE FORCE M.D.s

AT the Apollo Theater in Harlem, four young men are high-stepping and singing ``Love is a house/ You've got the key...,'' and the audience is on its feet, waving house and car keys in the air, swaying, singing, clapping, and cheering this lively foursome known as the Force M.D.s. Just a few years ago, this quartet was singing on the Staten Island Ferry and passing the hat. The group got its first big break when it signed with Tommy Boy Records, a New York-based independent label. The group's third LP, ``Touch and Go,'' scored high on the Billboard-magazine charts. Then, after a successful European tour, where the group opened for Madonna, the Force M.D.s toured the United States on their own.

Now, after several months outside the spotlight, the Force M.D.s are about to return with a new stage show and a new album, due later this spring. Word has it that they'll be adding a tougher ``street'' edge to the smooth harmonies that have become their trademark.

The Force M.D.s - Mercury and Trisco, and brothers T.C.D. and Stevie D. - grew up on Staten Island and have been singing together since they were children. They say that ``Force'' stands for their struggles coming up as young singers, and ``M.D.s'' stands for ``musical diversity.'' In an interview at Tommy Boy, T.C.D., whose smooth falsetto has been compared to Smokey Robinson's, explained how the group got started.

``My mother used to go to church a lot and come back home singing gospel hymns and stuff like that, and we used to join in with her. We started listening to the Jackson Five - that was the first group that caught our eye. I said, `Steve, look at the way they're dancin'!' He said, 'Oh, wow, I'm checkin' it out.'''

The Force M.D.s do some fancy foot-work in their stage show, and Stevie D. does a great imitation of Michael Jackson.

When the group started, it went by the name Force MC's, and it was mainly a rap group. Said Stevie D., ``We had a different style from a lot of rappers out there. Everybody thought we'd be big rappers, but we felt more comfortable singing.''

Now, as the rap genre expands to include more diverse musical elements and even some singing, the Force M.D.s say they will have some ``hiphop'' on their new album. But they won't betray their fans who love songs like their hit ballads ``Here I Go Again'' and ``Tender Love.''

As one audience member at the Apollo Theater remarked, ``These are the guys who will bring back slow dancing.''

Whether it's ballads or hiphop, the Force M.D.s look for a certain feeling in a song. ``You hear a lot of groups, and they harmonize and stuff, but it's too well planned,'' said T.C.D. ``With us, the harmony just flows. It's natural. It's something .... I don't know what it is!''

Added Mercury, ``We're not like your average stars: We're very real people; we're down to earth; we love performing and making people happy. We feel better playing in front of a lot of people than a few people, because we get to express ourselves more. I get high off the crowd; it lifts my whole spirit up.''

Mercury loves to work before a crowd (``He's the big mouth of the group,'' said T.C.D.), while Stevie is a playful clown, and Trisco and T.C.D. usually take the lead on the romantic ballads.

Said T.C.D., ``Our music is directed to those who believe in love and still believe in a song. We're mainly directing our songs to young, positive people. ... We want to give them a clear picture that anything you can do in this world, any little knack - just try to perfect it and, believe me, you'll be somebody. And you'll be doing something great someday. We're just trying to give people a little hope.''